As the Port of Miami tunnel project continues, lots and lots of dirt is piling up in Virginia Key.

So far, 250,000-cubic-yards of crushed limestone have been removed by Harriet, the tunnel boring machine.

"It is an incredible amount of dirt," said Jeovanny Rodriguez, the City of Miami Assistant Planning Director.

The material that is being excavated is being trucked there for a good reason.

"This was a City of Miami landfill from about 1961 to the late 70's when it was closed down," said Alice Bravo, the City of Miami Assistant City Manager.

The old landfill didn't have a lining so the soil is contaminated. Now, workers will put an environmental cap on the landfill and reclaim a prime parcel of land for public use.

"In this area, you will have four softball fields. Here, you would have four soccer, football fields and you would also have four tennis courts," said Bravo.

The boring at the port has temporarily stopped while they turn the drill around and get set to dig back to Watson Island. The conveyor belt that transported the fill has been dismantled because they will take the rest of the dirt out by the port.

"We are just about half, midway through it. We have received so far 250,000-cubic-yards," said Rodriguez.

The crushed limestone is classified as clean fill. The city needs 525,000-cubic-yards of it to cover an area 120-acres that's three feet deep. If the city needed to buy the fill, it would cost more than $20 million.

"It is hard to come by and just as fortunate we are that the tunnel contractor is transporting the material here," said Bravo. "So, that in itself would have represented a substantial cost to the city."